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Bent pushrod

After a major engine rebuild (mostly done by professional machine shop), the engine started and ran beautifully for about 100 miles.
Suddenly things went south - diagnosis.. a bent pushrod on cylinder #2 exhaust valve.
Most obvious cause would be a stuck valve but that does not appear to be the problem. No other cause that I can think of??
Installed a new pushrod (from Moss) and, again, the engine is running great, about 100 miles so far. I'm keeping my fingers crossed, hoping it was a freak event.
However, would very much appreciate any input.
The ignition timing was quite retarded (my fault) and an old timer at a local repair shop mentioned he vaguely remembers this sometimes causing damage to a pushrod on older engines.
Again, any input very welcome.
Thanks

Re: Bent pushrod

I have to assume and hope!!! the guides etc were checked for clearances. I used an established/reputable machine shop with lots of experience on old engines of all types.
I'll put on some miles/hours over the next few weeks and report back. Thanks.

Re: Bent pushrod

There are 2 different types of pushrod diameters out there; the 5/16 pushrod that are stock and older and maybe did it all time--- BEND. They also have 3/8 pushrods; they are beefy and do not bend; we used to talk more about it.
Pease out
steve

Re: Bent pushrod

I was fortunate that the bronze guide seizure became apparent as soon as the engine reached operating temp after rebuild. It involved 2 exhaust valves and was caught before the push rods were damaged.
Berry

Re: Bent pushrod

Originally Posted by titanic

I was fortunate that the bronze guide seizure became apparent as soon as the engine reached operating temp after rebuild. It involved 2 exhaust valves and was caught before the push rods were damaged.
Berry

Out of curiosity, what were the symptoms that had you shut the engine down when the valves tightened up in the guides?

Re: Bent pushrod

The engine started to run rough as the temp increased. With the valve cover removed, I could see the valves sticking. I removed the head, disassembled it, and could see traces of bronze on the valve stems. The machine shop appologized, re-reamed the guides, and no further problems.
Berry

Re: Bent pushrod

Sounds like your valve train is binding. Find someone that knows what they are doing and have them check it. Poolboy had this happen with his after a rebuild. Turned out to be spring bind if I remember right.

Re: Bent pushrod

The car's PO built that engine, Tom.
The cam and tappets got wiped out.
The problem must have been a combination of valve springs, cam selection, and rocker arm ratio...anyway it ran like that for 20,000 miles....
The same head, the same valve guides, the same seats, the same push rods and most of the same valves are in the current version of that engine, going on 30,000 miles.